In the operation of a copper vapor laser, the copper may become unavailable for lasing by condensation at the cool ends of the laser tube. Various wicks may be inserted near the ends of the laser tube to serve both as condensers for the copper vapor and as conduits to allow flow by capillary action of the liquid copper back into the hot zone of the laser where it is revaporized. However, the wicks may diminish the useful interior bore of the laser, therefore it would be desirable to provide a wicking surface which is thin and coated onto the inner surface of the laser bore.
One problem is that the laser tube, commonly made of alumina or other ceramic, does not readily receive coatings wettable by liquid copper and which would withstand the internal temperatures of the laser for an extended period of time without refinishing.
The present invention is directed to a method for providing coatings for the interior of a copper vapor laser tube which strongly adhere to the alumina and form uniform surfaces which are wettable by liquid copper.